JPH10266065A - Measurement of weft count in fabric and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of measuring weft count in a fabric quickly and accurately by use of laser beams and an optical sensor. SOLUTION: Laser beams emitted by the laser 6 of an emitter 1 are throttled so as to be smaller than the diameter of each of wefts woven in a fabric 4 as the target to be measured and irradiated on the fabric 4, and the transmitted light Lt is received by the optical sensor 10 of a light receiver 2, and based on the frequency of the light thus received, the objective weft count woven in the fabric 4 is measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the number of wefts in a cloth using a laser beam and an optical sensor.

[0002]

2. Description of the Related Art Of the fabrics, the warp and the weft are woven so as to be at right angles to each other, that is, the fabric is generally sold in units of length. . However, the length always and sometimes greatly differs depending on the process conditions at the time of measurement (immediately after weaving, before or after dyeing, immediately before shipping), and depending on the method of applying tension. For this reason, even if the weft is woven according to the standard, it may be treated as a defective product because the length is insufficient. Until now, the appearance of such defective products has been considered inevitable.

[0003] However, this problem can be solved, for example, by reference to the number of weft yarns per unit length during weaving, that is, the density (number of weft yarns / inch).
In other words, the number of wefts itself is taken as a measure of length, and the number of wefts contained in the entire length of a fabric or a woven fabric (hereinafter simply referred to as fabric unless otherwise specified) is defined by the number of wefts per inch specified at the time of design. This is because the quality of the fabric to be inspected can be determined without being influenced by the situation at the time of measuring the length. In particular, the density of the weft affects the color spots and the texture at the time of dyeing, and if the density is not in accordance with the design or the standard, the product value is reduced.

However, although a technique for counting the number of wefts constituting a fabric during weaving is known, it is difficult to count the number of wefts of a woven fabric. Technology did not exist. Therefore, an object of the present invention is to provide an apparatus for measuring the number of wefts of a cloth, which can measure the number of wefts within a very small error range even for a cloth or a woven cloth woven at a high density and at a considerably high speed. .

[0005] Further, the present invention measures the real-time weft density of a fabric at a portion where the weaving process is completed, and feeds back the measured data so that the weft density of the portion during the weaving can be always kept constant. It is an object to provide a number measuring device.

[0006]

According to a first aspect of the present invention, there is provided a method for measuring the number of wefts in a cloth, the method comprising the steps of: It is squeezed smaller than the diameter and irradiates the cloth to be measured, receives the transmitted light or scattered light,
The number of wefts woven into the fabric is measured from the frequency of the received light.

According to a second aspect of the present invention, there is provided a method for measuring the number of wefts on a fabric, wherein the wefts are woven into the fabric to be measured by using a laser beam as a fan-shaped beam pattern. Irradiating in the form of a thin line along the folding direction, receiving the transmitted light or the reflected light of the scattered light, converting the intensity signal of the received light into a rectangular wave, and converting the rectangular wave into the fabric. It is characterized in that the number of wefts woven into the fabric is measured.

In order to achieve the above object, the apparatus for measuring the number of wefts of a fabric according to the present invention is characterized in that a laser beam narrowed down to a diameter smaller than the diameter of the weft woven into the fabric to be measured is used. It is characterized by comprising a means for irradiating, a means for receiving transmitted light or scattered light of the irradiated laser beam, and a means for measuring the number of wefts woven into the cloth from the frequency of the received light.

According to a fourth aspect of the present invention, there is provided an apparatus for measuring the number of wefts on a fabric, wherein a laser beam is woven into the fabric to be measured as a fan-shaped beam pattern in order to achieve the above object. Means for irradiating so as to form a thin line along the folding direction, means for receiving transmitted light or scattered light of the irradiation laser beam, and means for converting an intensity signal of the received light into a rectangular wave, Means for measuring the number of wefts woven into the fabric from the rectangular wave.

According to a fifth aspect of the present invention, at least two of the irradiating means and the light receiving means are arranged at predetermined intervals.

According to a sixth aspect of the present invention, the light receiving means includes a pair of light receiving elements disposed close to each other, and the laser beam is radiated from the irradiating means to only one of the light receiving elements. The other light receiving element is arranged so as to be able to receive light from the surrounding environment, and the measuring means has means for removing the influence of the light by the difference signal between the light receiving signals of the pair of light receiving elements. And

The device according to claim 7 is characterized in that the means for removing the influence of the miscellaneous light is a differential circuit for taking the difference between the intensity of the light receiving signals of the pair of light receiving elements and outputting the difference.

[0013]

Embodiments and examples of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of an apparatus for measuring the number of wefts on a fabric for implementing the method for measuring the number of wefts on a fabric according to the present invention. The method and apparatus according to the present embodiment are arranged so that the laser beam is used to measure the diameter of the weft of the cloth to be measured (if the maximum density is 10 yarns / mm, 1
(About 00 μm), and irradiate the thin cloth with a thin cloth, and measure the number of wefts from the period of the transmitted light, that is, the frequency.

In FIG. 1, reference numeral 1 denotes a light emitting unit, 2 denotes a light receiving unit, 3 denotes a data processing unit, and 4 denotes a cloth to be measured. The light emitting section 1 is configured by housing a laser 6 and a focusing lens 7 in a light shielding cylinder 5. The light receiving section 2 is configured by housing a condenser lens 9 and an optical sensor 10 in a light shielding cylinder 8. Further, the data processing unit 3 includes an amplifier 11, ΔV
The apparatus comprises a detector 12, a counter 13, a comparator 14, a marker writing device 15 for fabric, and a preset circuit 16 for presetting a predetermined number of wefts. When the value reaches a preset value, a predetermined marker is written on the cloth 4 by the marker writing device 15 using ink or the like.

The spacing between the wefts of the fabric 4 is considered to be substantially the same as the yarn diameter d. In order to clearly determine the attenuation of the transmitted light Lt, the laser beam L on the irradiation surface of the fabric 4 must be at least separated by the yarn. It is desirable to narrow down sufficiently smaller than the diameter d. Therefore, the laser 6 has a He—Ne laser (wavelength λ = 63) having better properties than an inexpensive semiconductor laser.
It is preferable to use an Ar ion laser (wavelength λ = 547 nm) which has higher attenuation or scattering depending on the color of the cloth 4, that is, has higher sensitivity. The aperture diameter a of the laser beam L by the focusing lens 7 is proportional to the product of the focal length f of the focusing lens 7 and the wavelength λ.
A lens having the smallest possible focal length f is preferable. However, the selection may be made in consideration of the fact that the distance from the surface of the cloth 4 becomes too small to be unsuitable for practical use, and that the narrowing diameter a becomes large due to the occurrence of a pin-poke state due to the shift of the focal position. . For example, for a He-Ne laser beam (wavelength input = 633 nm), the focal length f = 15 mm,
When a focusing lens having a working distance 1 = 6 mm and a magnification of 10 is used, the aperture diameter a is about 25 μm.

The light receiving section 2 focuses not only the transmitted light Lt but also the diffracted light and the scattered light on the light receiving element of the optical sensor 10 by the condenser lens 9 to improve the accuracy. However, it is possible to detect a light intensity change period (for example, a period T = 0.1 ms, that is, a frequency of 10 kHz) corresponding to a high density (for example, a maximum of 10 lines / mm) and a high-speed weave (for example, a maximum of 1 m / s). In addition, as a light receiving element of the optical sensor 10, a PIN photodiode for higher speed is most preferable. With such a configuration of the light receiving unit 2, when the cloth 4 is white, the intensity change can be detected accurately and accurately by a red He-Ne laser beam. In some cases, an ion laser can be detected with higher sensitivity.

Next, the measurement when the cloth 4 is thin and the result will be described. FIG. 2 shows a spectrum of transmitted light Lt when the cloth 4 is scanned at a constant speed v (m / s) with the laser beam L whose diameter is reduced as described above, and FIG. 3 is a microscope of the cloth 4 as a sample. Shown in the picture. FIG. 2 shows that the sample cloth is about 15 cm.
/ S, and the change in transmitted light intensity is a signal waveform stored in a digital sampling oscilloscope.
(A) shows an output signal from the amplifier 11 and (B) shows an output signal from the ΔV detector 12. Note that the upper portion of the signal is cut off in (A) because the signal was cut by the chopper, and the output was reduced in some places because the laser beam L used for scanning was not only the weft but also both the weft and the warp. Is transmitted. When such a signal passes through the ΔV detector 12, the signal becomes as shown in FIG. The counter 13 can accurately measure the number of wefts constituting the fabric 4 from such a signal waveform.

The frequency spectrum at this time is shown in FIG.
As shown in the figure, there is a sharp peak at only about 130 Hz, and the half width is about 3 Hz. This frequency spectrum is necessary for grasping the general characteristics of the weaving method of the cloth 4, and the fact that there is a sharp peak only at one place means that the intensity of the transmitted light Lt is a simple sine wave. Corresponding to To further improve the accuracy of the measurement,
It is preferable to perform the same measurement at two or more places on the cloth 4 at the same time so as to minimize measurement errors. FIG. 4
FIG. 4B shows a change in the light intensity of the transmitted light Lt received by the light receiving unit 2, and the frequency spectrum shown in FIG.

Incidentally, the accuracy (accuracy) required for the above-described measurement is 99.9% or more. This can be easily achieved for simple structured fabrics, but to achieve this for a variety of complex knitted fabrics, the same counting device can be used at the same time to determine which one is the correct. It is conceivable to use the results. For example, a device with a 3% counting error
When using two devices, the probability that both devices make a mistake at exactly the same timing is 0.09% (= 0.03 × 0.03) <
Since it is 0.1%, counting with an accuracy of 99.9% or more can be easily performed. Of course, it is more practical if the accuracy can be obtained with one device. In order to realize this, for example, when the intensity change of the transmitted light Lt or the scattered light Ls is suddenly disturbed and counting becomes impossible, judgment is made from before and after that, and a measurement error is automatically corrected by software (a so-called method). Interpolation method) can be considered.

In realizing the above-described embodiment,
It is necessary to adopt a structure of the light emitting section 1 which can accurately focus the focal position of the laser beam L on the cloth 4 to be measured. However, this incorporates a hemispherical glass at the tip of the focusing lens 7 and ensures the contact with the cloth. What is necessary is just to have the structure which does. In addition, since light from the surroundings cannot be ignored, the light projecting system including the light emitting unit 1 and the light receiving system including the light receiving unit 2 may be integrated into a hood like a camera.

FIG. 5 is a perspective view showing a second embodiment of a cloth weft number measuring apparatus for carrying out the cloth weft number measuring method according to the present invention. The method and apparatus according to the present embodiment are thick cloths that occupy most of high-grade cloths, and the knitting method is complicated when viewed from a microscopic scale, but is clearly periodic when viewed from a macroscopic level (for example, by visual observation). A certain cloth is to be measured, and a laser beam is radiated in a fan shape, and the cross-sectional shape on the irradiation surface is made linear (for example, about 1 mm × 0.1 mm), and the intensity change of the scattered light is counted. Is what you do. That is, a light-shielding curtain cloth or a cloth having different oblique patterns on the front and back sides, for example, the cloths shown in FIGS. 6A and 6B are measured. FIG. 6A shows the front side of the fabric, and FIG. 6B shows the back side.

That is, in the case of a thick cloth, the laser beam L
Is not expected, and the S / N ratio of the signal becomes small. Therefore, the number of weft yarns is measured from the intensity change of the scattered light on the surface of the cloth 4. The cloth 4 in this case has a very complicated shape even from the naked eye observation, and it is important to analyze in advance the frequency spectrum. For this reason, in the apparatus of the present embodiment, the light emitting unit 1 and the light receiving unit 2 are arranged on the same side with respect to the cloth 4, and the data processing unit 3 is further provided with a spectrum analyzer 19 including an FFT 17 and a computer 18. .

The method and apparatus according to the present embodiment receive the scattered light Ls of the laser beam L 'on the surface of the cloth 4 by the light receiving unit 2 and analyze the frequency component thereof to grasp the characteristics of the method of knitting the cloth 4. The number of weft yarns is measured from the relationship with the feed speed v of the cloth 4 at that time. Light emitting unit 1 and light receiving unit 2
Is a cloth 4 whose linear laser beam L 'is to be measured.
And place it along the stitches. For example, when the stitches appearing on the surface of the cloth 4 are oblique patterns as shown in FIG. 7, the box 21 and the light emission housed therein are arranged so that a linear laser beam L 'can be irradiated in parallel to the oblique patterns. The unit 1 and the light receiving unit 2 are arranged. The width w of the laser beam L 'is equal to the interval d of the oblique pattern.
And the length l is about 3 to 5 times, but the scattered light L
The frequency spectrum of s is determined by the feed speed v of the cloth 4 and the cloth 4
The cross-sectional shape of the laser beam L 'on the irradiation surface varies depending on the cross-sectional shape of the laser beam. It is best to measure. The scattered light Ls received by the light receiving section 2 includes reflected light as well.

With the structure described above, a linear laser beam L ′ is emitted from the light emitting section 1 to the surface of the cloth 4 and the scattered light Ls ′ is received by the light receiving section 2. The received light intensity signal is substantially sinusoidal. After this light receiving signal is amplified by the amplifier 11, it is converted into a rectangular wave by the ΔV detector 12, and the converted wave is counted by the counter 13.

As shown in FIG. 8, the apparatus of the present embodiment is housed in a box 21 having an opening at the lower side to block light from the surroundings, and the upper part of the box 21 is attached to a drive unit 22 so that the cloth 4 may be moved in the longitudinal direction, or the measuring device may be fixed and the fabric 4 may be moved as in the previous embodiment.

FIGS. 9 to 11 show the measurement results obtained with this apparatus. In each case, the upper part shows the output intensity itself from the light receiving unit 2, and the lower part shows the output of the ΔV detector 12. 9 shows an ideal case where the linear laser beam L ′ is parallel to the oblique pattern of the cloth 4, FIG. 10 shows a case where the laser beam L ′ is slightly displaced, and FIG.
Indicates the case where the pattern crosses the oblique pattern. The output of FIG. 10 not only has a smaller amplitude of the output intensity itself than the output of FIG. 9, but the waveform itself is distorted from a sinusoidal shape. However, if the threshold value of the ΔV detector 12 is appropriately selected, a counting error does not occur with such a deviation. In FIG. 11, counting errors may occur. These FIGS. 9 to 1
The relationship between the linear laser beam L ′ corresponding to 1 and the oblique pattern is shown as S9, S10, and S11 in FIG.

That is, it is preferable that the linear laser beam L 'be parallel to the oblique pattern of the cloth 4 as much as possible, but it is not always possible to arrange it in this way. Therefore, in order to achieve the required accuracy, for example, 99.9% or more, the fact that the amplitude of the output signal of the light receiving element becomes small when it deviates from the parallel state is utilized. The direction may be rotated, but the direction adjustment may not be able to follow the speed at the time of counting the weft of the fabric 4 moving at a speed of 1 m / s or more. Are installed at different positions and either one of them is counted by the signal that is correctly counted, or if a temporary counting error occurs, the correct counting before and after that is used to correct the error section, so-called interpolation method is used Can be adopted. For measurement with two devices, the width of the fabric 4 (approximately 1
.About.2 m), there is almost no possibility that a counting error will occur at the same time, as described above.

FIG. 12 shows an example of measurement results for several types of fabrics by the apparatus of this embodiment. Although the measurement accuracy was 99% or more, since the cloth to be measured was only the oblique pattern, the actual number of wefts had to be multiplied by a factor of several depending on the weaving method.

By the way, the place where the cloth is measured as described above is called a detection field, where a person detects a scratch or a color spot on the cloth, and is several times brighter than a normal room. That is, the brightness in the room becomes miscellaneous light, and the light reception signal in the light receiving section 2 may be buried in the miscellaneous light. High output (about 2
This point can be solved by using a semiconductor laser of 0 mW) and the light receiving unit 2 is shielded from light by a large box, but this is not always possible in an actual measurement place. Therefore, a method for removing noise that can be employed in the embodiment of the present invention will be described below.

This removing method is a so-called active (active) light removing method capable of positively removing the influence of the light even in a bright place. As shown in FIG. 13, the light receiving sections 2a and 2b having the same structure are used. Are arranged close to each other, and only one of the light receiving portions 2a is irradiated with the laser beam L as a signal,
The difference between the outputs of the two light receiving units 2a and 2b is extracted.
In the drawing, reference numeral 30 denotes a rough light source such as a fluorescent lamp, and reference numeral 31 denotes a light shielding plate disposed on the front surface of the light receiving surface of the light receiving unit 2b.

FIG. 14 is a circuit diagram showing a differential circuit 40 for extracting the difference between the outputs of the light receiving sections 2a and 2b. The intensity of the miscellaneous light NL incident on the light receiving elements 2a and 2b is N
1, N2 and the intensity of the laser beam L incident only on the light receiving element 2a is L1, and the current I
1 is

I1 = k1 (L1 + N1) The current I2 generated in the light receiving element 2b is

## EQU2 ## I2 = k2 · N2. Here, k1 and k2 are coefficients representing the overall light receiving sensitivity of both light receiving elements 2a and 2b, and ideally k1 = k2. If the light receiving elements 2a and 2b are arranged close to each other, the miscellaneous light NL substantially incident on the light receiving elements 2a and 2b
Are considered to be almost equal.

The differential circuit 40 includes a pair of amplifiers 41a, 41
b, and a differential amplifier 42, the amplifier 41a is connected to the light receiving element 2a, the amplifier 41b is connected to the light receiving element 2b, and the differential amplifier 42 inputs the outputs of both amplifiers 41a and 41b to perform differential amplification. It has become. As is well known, if the outputs of both amplifiers 41a and 41b are Ea and Eb, the voltage gain E0 of the differential amplifier 42 is

E0 = [E1０ {R4 (R1 + R2)} / ｛R
1 (R3 + R4)}]-{E2 / (R2 / R1)}, and if (R2 / R1) = (R3 / R4),

## EQU4 ## E0 = (E1-E2). (R2 / R1) As a result, the output due to the light NL is canceled, and only the output signal from the laser beam L free from the influence of the light can be obtained.

Of course, when the outputs N1 and N2 due to the miscellaneous light NL are different from each other to such an extent that they cannot be ignored under some circumstances, the mounting state of the light receiving elements 2a and 2b may be devised, or one of the amplifiers 41a and 41b may be used. The amplification degree may be adjusted so that the outputs N1 and N2 due to the miscellaneous light are approximately equal. Note that the output may vary depending on environmental factors such as vibrations received by the light receiving elements 2a and 2b. Therefore, if the light receiving elements 2a and 2b are mounted on the same support system, the external factors such as the vibrations received by the two light receiving elements 2a and 2b are completely reduced. Become the same,
External errors can also be removed.

FIGS. 15 to 18 show examples of measurement results obtained by the method and the apparatus according to the present embodiment. FIG. 15 shows the light receiving element 2
a, b output when only one of the light is received, FIG. 16 shows the output by the laser beam L, and FIG. 17 shows the sum of both outputs. FIG. 18 shows the result of differentially amplifying the output of only the light source 30 with the light shielding plate 31 removed. As a result of the differential amplification, the light voltage of 2.92 V becomes 18.85 mV, that is, almost zero.

That is, in any of the above-described two embodiments, except for the one such as toweling, in which no regularity can be found with the naked eye (the one having a complicated frequency spectrum), the one in which regularity can be found, in other words, the scattering light When the frequency spectrum of the light intensity change has a peak at one place, the number of wefts can be accurately measured.

[0035]

The method and apparatus for measuring the number of wefts of a fabric according to the present invention are as described above. Therefore, the method for measuring the number of wefts of a thin fabric, a thick fabric and fabrics of various weaves is inexpensive and practical. In addition, there is an effect that it is possible to perform accurately and accurately at high speed and high accuracy. Further, the method and apparatus of the present invention can measure at high speed, so that the number of wefts and density can be measured in real time while weaving the fabric, and the measurement results can be fed back to the number of wefts and the density of the portion during weaving. There is also an effect that can be made constant.

The apparatus according to the sixth and seventh aspects of the present invention, in addition to the above-mentioned common effects, is not affected by ambient light, and can be actively used even in a bright and noisy environment. There is an effect that accurate detection can be performed by removing the influence of noise.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an apparatus for measuring the number of wefts of a fabric for implementing a method of measuring the number of wefts of a fabric according to the present invention.

FIG. 2 is a diagram showing a spectrum of transmitted light when a cloth is measured by the apparatus of FIG. 1;

FIG. 3 is a diagram showing a micrograph of a cloth to be measured by the apparatus of FIG. 2;

4A is a diagram illustrating a frequency spectrum of the transmitted light in FIG. 2 and FIG. 4B is a diagram illustrating a change in light intensity of the transmitted light.

FIG. 5 is a perspective view showing a second embodiment of a cloth weft number measuring device for carrying out the cloth weft number measuring method according to the present invention.

FIG. 6 is a view showing a micrograph of a cloth to be measured by the apparatus of FIG. 5;

FIG. 7 is an enlarged view of a stitch (slanted pattern) of a cloth to be measured by the apparatus of FIG. 11;

8 is a perspective view showing a use form of the device of FIG.

9 is a diagram showing a measurement result of the apparatus of FIG. 5, and is a diagram showing an ideal case where a linear laser beam is parallel to a slant pattern on a cloth.

FIG. 10 is a view showing a measurement result obtained by the apparatus shown in FIG. 5, and is a view showing a case where a linear laser beam slightly shifts to a slant pattern on a cloth.

11 is a diagram showing measurement results obtained by the apparatus shown in FIG. 5, and is a diagram showing a case where a linear laser beam deviates from a slant pattern on a cloth and a counting error occurs.

FIG. 12 is a diagram showing an example of measurement results for several types of fabrics in the apparatus of FIG. 5;

FIG. 13 is a conceptual diagram showing a method and an apparatus for removing miscellaneous light when the method for measuring the number of wefts of a fabric according to the present invention is performed in a bright place.

FIG. 14 is a circuit diagram showing an example of a differential circuit used in the device of FIG.

FIG. 15 is a diagram illustrating an example of miscellaneous light output when light is received by only one of the light receiving elements in the device of FIG. 5;

FIG. 16 is a diagram showing an output example when only a laser beam is irradiated on a light receiving element in the apparatus of FIG. 5;

FIG. 17 is a diagram showing the sum of the outputs of FIGS. 15 and 16;

FIG. 18 is a diagram illustrating an example of differential output when light is received by both light receiving elements in the device of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light-emitting part 2 Light-receiving part 2a, 2b Light-receiving part 3 Data processing part 4 Fabric to be measured 5, 8 Light-shielding cylinder 6 Laser 7 Focusing lens 9 Condensing lens 10 Optical sensor 11 Amplifier 12 △ V detector 13 Counter 14 Comparison Instrument 15 Marker writing device 16 Preset circuit 17 FFT 18 Computer 19 Spectrum analyzer 21 Box 22 Drive device 30 Miscellaneous light source 31 Light shielding plate 40 Differential circuit 41a, 41b Amplifier 42 Differential amplifier L Laser beam L 'Linear laser beam Lt Transmission Light Ls, Ls' Scattered light NL Miscellaneous light

Claims (7)

[Claims] 1. A laser beam is squeezed to a diameter smaller than the diameter of a weft woven into a cloth to be measured and irradiates the cloth to be measured, the transmitted light or the scattered light is received, and the frequency of the received light is received. A method of measuring the number of wefts woven into the cloth from the above. 2. A laser beam is irradiated as a fan-shaped beam pattern so as to form a thin line along the folding direction of the weft woven into the cloth to be measured, and the transmitted light or the reflected light of the scattered light. And converting the intensity signal of the received light into a rectangular wave, and measuring the number of wefts woven into the fabric from the rectangular wave. 3. A means for irradiating a laser beam narrowed down to a diameter of a weft woven into a cloth to be measured, a means for receiving transmitted light or scattered light of the irradiated laser beam, and a means for receiving the received light. Means for measuring the number of wefts woven into the fabric from the frequency of the weft. 4. A means for irradiating the laser beam as a fan-shaped beam pattern so as to form a thin line along the folding direction of the weft woven into the cloth to be measured, A fabric comprising: means for receiving scattered light; means for converting an intensity signal of the received light into a rectangular wave; and means for measuring the number of wefts woven into the fabric from the rectangular wave. Weft count measuring device. 5. An apparatus according to claim 3, wherein at least two of said irradiating means and said light receiving means are arranged at a predetermined distance from each other. 6. The light receiving means includes a pair of light receiving elements arranged close to each other, the one light receiving element being arranged to be able to irradiate the laser beam from the irradiating means, and the other light receiving element being provided with a surrounding area. 6. The light receiving device according to claim 3, wherein said light receiving means is arranged to receive light from the environment, and said measuring means has means for removing an influence of said light by a difference signal between light receiving signals of said pair of light receiving elements. Device for measuring the number of wefts of any fabric. 7. The number of wefts of a fabric according to claim 6, wherein the means for removing the influence of the miscellaneous light is a differential circuit that outputs the difference in the intensity of the light receiving signals of the pair of light receiving elements. Measuring device.